Air-cushion winding machine

ABSTRACT

In a winding arrangement for material in sheet form, a radially displaceable box-like structure extending over the entire width of the sheet form material is arranged over the roll of material, being provided underneath with openings through which issues an airstream which is directed onto the surface of the roll and which keeps the box-like structure afloat on the lines of an air cushion. In this way, the sheeting is applied uniformly to the roll, especially in the case of thin sheeting, so that creasing is avoided.

United States Patent Bruck et al.

AIR-CUSHION WINDING MACHINE Inventors: Rolf Bruck, Opladen; Kurt Meister,

Leichlingen, both of Germany Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany Filed: Aug. 6, 1973 Appl. No.: 386,015

Assignee:

Foreign Application Priority Data Aug. 12, 1972 Germany 2239778 U.S. Cl 242/55; 226/97; 242/67.] R;

Int. Cl. B65H 23/24 Field of Search 242/55, 471, 76, 75.2, 242/66; 226/95, 97

References Cited UNITED STATES PATENTS Fridolph 242/66 Oct. 14, 1975 3,216,638 11/1965 Brickle et al. 226/97 3,304,017 2/1967 Buteux et al 242/55 3,744,693 7/1973 Greiner 226/97 3,749,328 7/1973 Dusenbery 242/55 Primary Examiner-George F. Mautz Attorney, Agent, or Firm-Connolly and Hutz [57] ABSTRACT In a winding arrangement for material in sheet form, a radially displaceable box-like structure extending over the entire width of the sheet form material is arranged over the roll of material, being provided underneath with openings through which issues an airstream which is directed onto the surface of the roll and which keeps the box-like structure afloat on the lines of an air cushion. In this way, the sheeting is applied uniformly to the roll, especially in the case of thin sheeting, so that creasing is avoided.

9 Claims, 7 Drawing Figures U.S.Patent Oct. 14,1975 Sheet10f3 3,912,186

FIG] FIG. 2

.U.S. Patent Oct..14, 1975 Sheet 2 of 3 3,912,186

US. Patent Oct. 14,1975 Sheet3of3 3,912,186

FIG. 7

AIR-CUSHION WINDING MACHINE This invention relates to a winding machine for sheetform material. Winding machines are used for winding coated or uncoated films or paper in sheet form into rolls. The invention is particularly suitable for winding extremely thin, wide films into rolls at high winding speeds. V

In practice, the sheets of film to be wound into rolls under low tension and at high winding speeds are inevitably diverted to one side by air pockets. Accordingly, it is completely difficult to produce crease-free packages ,with strictly parallel edges.

Although it is possible by increasing the film tension to displace most of the air and, hence, to obtain parallel edges, any increase in tension in the case of extremely thin films (less than 0.02 mm thick) readily results in irreversible deformation of the films.

Contact rollers are known which rest on the package and which are intended to apply the sheet-form material uniformly to the roll or package onto which it is wound. Naturally, stringent requirements have to be imposed upon the precision of the package in regard to its rotation and upon the parallel position of the contact roller to the package. In general, these requirements cannot be satisfied because the cardboard tubes used in practice are not completely circular. In addition, it is generally not possible to prevent the tube from being eccentrically mounted on the winding shaft. In addition to this there are the differences in the thickness of the sheet-form material, with the result that the package locally develops beads. The eccentric rotation of the roll and the resulting irregular contact of the contact roller have an adverse effect upon the properties of the roll, especially in the case of thin, wide films of low transverse stiffness. The quality of the finished rolls is frequently inadequate.

It is also known that the beginning of a continuous sheet can be wound cleanly and safely onto the winding core by passing around the winding core an air stream which entrains and carries the sheet with it. Unfortunately, this arrangement can only be used for winding the beginning of the continuous sheet onto the core, but not for winding the entire length of continuous sheet into a roll. Nor does it enable a relatively high contact pressure to be applied to the sheeting. In the case of thin films, air pockets and creases cannot be avoided, especially at high winding speeds.

The object of the invention is to provide a winding machine which enables extremely thin, wide sheetform materials to be wound cleanly into rolls at high winding speeds. Another object of the invention is to avoid the sources of error referred to above.

According to the invention, these objects are achieved by virtue of the fact that a substantially radially displaceable box-like structure extending over the entire width of the sheeting is arranged above the roll, being provided underneath with one or more openings which allow through an air stream directed onto the surface of the roll which just compensates the gravitational force of the box-like structure and keeps it afloat on the lines of an air cushion.

The gravitational force of the box-like structure can also be replaced by another elastic opposing force. In addition to the gravitational force, an elastic force also acts on the box-like structure. In its most simple form, the elastic force is generated by means of springs which limit the radial movement of the box-like structure. An-

other possibility is to generate the elastic force by means of a pneumatic piston.

The box-like structure is advantageously mounted i guide rails. In an alternative embodiment, the box-like structure is mounted on a lever whose pivot is situated level with the final sheet-guide roller before the winding core.

The box-like structure is best designed in such a way that it contains several air chambers connected to separate air supply lines. A slot or perforated plate is preferably arranged in the box-like structure before the airoutlet openings, providing for uniform distribution of the air.

The underneath of the box-like structure is best covered with an elastic material to prevent scratching of the sheet-form materials when, for example, the flow of air stops and the box-like structure rests on the sheeting. According to another aspect of the invention, the box-like structure is designed to rotate about an axis parallel to the winding axis. However, this feature is only applicable in cases where, as mentioned above, the box-like structure is mounted on a rotatable lever.

The invention is based on the air-cushion principle. The air issuing from the box-like structure keeps it afloat. The contact pressure applied to the surface of the sheeting is not governed by the amount of air blown in, but is derived from the weight of the box-like structure divided by the overall opening cross section for the issuing air. The contact pressure can be increased by applying additional weights to the box-like structure.

It is clear that the gravitational force of the box-like structure can be replaced by an elastic opposing force. The elastic opposing force is best generated by compression springs or pneumatically. Under the effect of the issuing air stream, the box-like structure is lifted off the surface of the sheeting and presses against the springs or against the hydraulic piston. In both cases, the degree of deformation is a measure of the contact pressure of the air cushion.

Higher contact pressures are required at high winding speeds than at low winding speeds. The optimum contact pressure for a certain material at a certain winding speed is governed by the diameter of the roll and can be kept constant throughout the entire winding operation. The throughput of air required is governed by the required safety clearance of the box-like structure from the surface of the roll.

To change the roll, the box-like structure is raised, temporarily stopped and replaced on the new roll. In order to avoid damage during roll changing, the underneath of the box-like structure is covered with an elastic material, for example foam rubber, and additionally coated with a dry lubricant.

The following major advantages are afforded by the invention. The air cushion guarantees uniform application of the sheeting over its entire width. In contrast to conventional contact pressure rollers, irregularities in the winding tubes and creases in the coated sheeting are unimportant because, even in their case, the sheetform materials are still wound into rolls under constant contact pressure. Since the contact pressure is applied in the absence of physical contact, the surface of the sheeting is not exposed to any real stressing, whereas in cases where the contact pressure is generated by means of contact rollers, it is exposed to locally heavy stress- The movement of the roll parallel to its axis is not impeded by the air cushion. Accordingly, in contrast to contact pressure rollers, it is possible to provide an edge-regulating means which counteracts any lateral traversing of the sheet-form material. The new contactpressure generator has hardly any components that are prone to wear with the result that little maintainence is required and reliability in operation is high.

In a modified embodiment of the invention, the gravitational force of the box-like structure is replaced by another elastic opposing force. The advantage of this is that the box-like structure does not have to be arranged vertically above the roll, but instead can be arranged at any point on a circle concentric to the roll. However, it is best arranged at that point at which the sheet-form material runs onto the roll.

One embodiment of the invention is described by way of example in the following with reference to the accompanying'drawings, wherein:

FIG. 1 illustrates the air-cushion principle with gravity.

FIG. 2 illustrates the air-cushion principle with gravity and an additional spring force.

FIG. 3 shows the air-cushion principle with an additional hydraulic force.

FIG. 4 shows the structure of the contact-pressure generator in section.

FIG. 5 shows the movable mounting of the contactpressure generator by means of lateral pivotal arms.

FIGS. 6 and 7 show the roll and contact-pressure .generator in vertical section and front elevation, re-

spectively.

According to FIG. 1, sheeting 1 is wound onto the roll 2. The roll 2 is fixed to a driven winding shaft. The contact-pressure generator 3 is mounted for vertical displacement by movement of its pin 3a in guide rails 4 above the roll 2. An air stream is blown onto the sheetingl through the openings in the bottom 5 of the contact-pressure generator 3 with such intensity that the contact-pressure generator 3 is raised. The contactpressure generator 3 then transfers its own weight to the sheeting being wound onto the roll without actually touching it.

According to FIG. 2, the contact-pressure applied by the contact-pressure generator 3 is intensified by an additional spring 6 reacting between block 4b and pin 3b. In this case, the contact-pressure is no longer independent of the clearance between the contact-pressure generator 3 and the sheeting 1, but instead increases with increasing clearance in accordance with the spring characteristic (elastic air cushion).

FIG. 3 also shows an elastic air cushion. In this case, however, the opposing force is applied by means of the hydraulic piston 7 reacting against pin 3c rather than by a spring. This embodiment is of advantage in cases where the opposing force has to be varied during operation.

FIG. 4 illustrates the structure of the contactpressure generator 3. It is divided up into several chambers 8 (similar to those'shown in FIG. 6) which communicate with separate air supply lines 9. A slotted plate 11 is situated above the air-outlet chamber 10. In this way, the air issues particularly uniformly. The underneath of the air-outlet chamber is provided with a through-perforated layer 12 of foam. The air pressure required to raise the contact-pressure generator 3 is generated by a fan (not shown) connected to the air supply lines 9.

According to FIG. 5, the contact-pressure generator 3 is displaceably mounted on pivotal arms 13. The pivot 14 for the pivotal arms 13 is situated far outside at a point vertically above the final sheet-guide roller 15 before the roll 2. The pivot 14 can also coincide with the axis of the sheet-guide roller 15 (shown in broken lines).

FIG. 6 again shows the compartmenting 8 of the contact-pressure generator. It also shows how the contactpressure can be increased by added weights 16. The contact-pressure generator 3 is suspended on the pivotal arms 13 for rotation about the shaft 17.

The winding operation is illustrated by the following Examples:

EXAMPLE I Sheeting 1120 mm wide and 0.025 mm thick was to be wound into a roll by means of the arrangement shown in FIGS. 1 and 2. The contact area of the contact-pressure generator 3 amounted to 3 X 100 cm 300 cm The total force of the contact-pressure generator, composed ofits own weight and the added weight, amounted to 9000 p so that a contact-pressure of 30 g/cm was applied to the surface of the roll. The air pressure building up inside the roll (static pressure) also amounted to 30 glcm The sheeting was wound under a tension of 10 kg at a speed of m/minute. The result was an extremely smooth, uniform and straight-edged roll. The sheeting showed no sign of creasing or deformation, even after prolonged storage.

If the same contact-pressure of additionally 30 g/cm were to be produced by increasing the winding tension in the absence of the air cushion, the sheet tension would have to be increased from l0 kg to 43.6 kg. This would produce extremely heavy distortion in the sheet- For comparison, identical sheeting was wound into a roll in the usual way, i.e. by means of a contact roller,

lunder comparable conditions. Creases were consistently formed in the roll, in addition to which the hardness of the roll (over its circumference) was irregular.

EXAMPLE 2 The arrangement described in Example I was again used, except that on this occasion the bearing pressure of the contact-pressure generator amounted to l g. The sheeting to be wound into a roll was thinner than in Example 1. Its thickness amounted to only 0.0l5 mm. The sheeting was wound under a tension of 6 kg at a speed of I00 m/minute.

Once again, satisfactory rolls were obtained although the conditions were considerably more critical and a total of 3000 meters of sheeting were wound onto one core.

It has been found that the optimum bearing pressure of the contact-pressure generator has to be determined in dependence upon the winding condition for each type of sheeting. However, the optimum value is not critical. Even with deviations of i 20%, satisfactory rolls were still obtained. Accordingly, the bearing pressure can be empirically determined without difficulty.

What we claim is:

1. An arrangement for winding sheet material onto a roll, comprising a radially displaceable structure extending over the entire width of the sheet, the structure being arranged above the roll, a radial force reacting against the structure and urging it towards the roll, the bottom of the structure having a substantial area and being provided with a plurality of openings which allow an air stream to be directed onto the surface of the roll which compensates for the radial force on the structure and keeps it from contact with the roll on an air cushion which causes the sheet material to be uniformly wound on the roll, the bottom of the structure comprising an elastic material having through perforations, the structure contains a plurality of laterally disposed air chambers, separate air supply lines connected to each of the laterally disposed air chambers, a plurality of openings from the air chambers, and a slotted plate arranged in the structure between the outlets from the air chambers and the air-outlet openings in the elastic material whereby uniform distribution of the air is provided.

2. An arrangement as claimed in claim 1, wherein the force comprises a gravitational force.

3. An arrangement as claimed in claim 1, wherein the force comprises an elastic force.

4. An arrangement as claimed in claim 3, wherein the elastic force is generated by springs.

5. An arrangement as claimed in claim 3, wherein the elastic force is generated by means ofa pneumatic pis- [OIL 6. An arrangement as claimed in claim 1, wherein the structure is mounted in guide rails.

7. An arrangement as claimed in claim 1 wherein pivotal arms are provided, the structure is mounted on the pivotal arms, a last sheet guide-roller disposed before the roll in guiding contact with the winding sheet before it engages the roll, the pivotal arm having a pivot, and the pivot is situated vertically above the pivot of the last sheet-guide roller before the roll.

8. An arrangement as claimed in claim 7, wherein a shaft disposed parallel to the winding axis is provided, and the structure is mounted to rotate about the shaft.

9. An arrangement as claimed in claim 1 wherein the elastic material comprises a foamed plastic having through perforations. 

1. An arrangement for winding sheet material onto a roll, comprising a radially displaceable structure extending over the entire width of the sheet, the structure being arranged above the roll, a radial force reacting against the structure and urging it towards the roll, the bottom of the structure having a substantial area and being provided with a plurality of openings which allow an air stream to be directed onto the surface of the roll which compensates for the radial force on the structure and keeps it from contact with the roll on an air cushion which causes the sheet material to be uniformly wound on the roll, the bottom of the structure comprising an elastic material having through perforations, the structure contains a plurality of laterally disposed air chambers, separate air supply lines connected to each of the laterally disposed air chambers, a plurality of openings from the air chambers, and a slotted plate arranged in the structure between the outlets from the air chambers and the air-outlet openings in the elastic material whereby uniform distribution of the air is provided.
 2. An arrangement as claimed in claim 1, wherein the force comprises a gravitational force.
 3. An arrangement as claimed in claim 1, wherein the force comprises an elastic force.
 4. An arrangement as claimed in claim 3, wherein the elastic force is generated by springs.
 5. An arrangement as claImed in claim 3, wherein the elastic force is generated by means of a pneumatic piston.
 6. An arrangement as claimed in claim 1, wherein the structure is mounted in guide rails.
 7. An arrangement as claimed in claim 1 wherein pivotal arms are provided, the structure is mounted on the pivotal arms, a last sheet guide-roller disposed before the roll in guiding contact with the winding sheet before it engages the roll, the pivotal arm having a pivot, and the pivot is situated vertically above the pivot of the last sheet-guide roller before the roll.
 8. An arrangement as claimed in claim 7, wherein a shaft disposed parallel to the winding axis is provided, and the structure is mounted to rotate about the shaft.
 9. An arrangement as claimed in claim 1 wherein the elastic material comprises a foamed plastic having through perforations. 